Blended polyamides



fie ite dorm. 1d, 3

BLENDED POLYAIES Merlin Martin Brubelrer, Boothwyu, ms, and Donald Broke iofimau and Frock C. McGrcw, Wgtou, Del... ossiguors to E. K. du Pout do Nemomc & t'loos oany, Wilmington, Del" a corporatiou o? Delaware No Drawing. Application April 11, 194i, Serial No. 388,184

l (31. 26il-78l 8 *Elaims.

This invention relates to polymeric materials and more particularly to the manufacture and treatment of solid structures consisting essentially of synthetic linear poly-amides of types such as described hereinafter. For convenience, the sold types will be referred to at times simply as poly-amides. Still more particularly, this invention relates to the manufacture and processing of filaments, fibers, pellicles, ribbons, films, sheets, and other like structures, consisting essentially of the said polyamides, as well as to textile or other products fabricated therefrom.

The said polyamidcs as a class are capable of being spun into filaments that can be drawn to produce molecular orientation along their fiber axes. The resulting oriented fibers, or fabrics formed therefrom, generally are characterized by relatively low water absorption, pronounced resistance to deformation and moderately slow recovery from strain. While these properties oi the polyamide articles render them esmcially suitable for many uses, there nevertheless are a number of more or less specialized fields of utility for which such articles are not altogether satisfactory. For instance, the low water absorption capacity of the polyemides makes it considerably more diflicult to subject them successfully to cer tain types of processing for which natural fibers similar or analogous to wool are especially adapted, by reason of their relatively high sfllnity for moisture. Furthermore, the fact that the water absorption capacities of the various polyamio'es roughly correspond. in degree, to certain desirable physical properties, particularly the ease with which the polyamides can be set in a form to which they recover after deformation, lends emphasis to the need which has arisen for the development of processes making possible the enhancement of the water absorption capacity of pclyamide structures.

This invention has as its primary object therefore the production of polyamide structures hav ing enhanced water absorption capacities, us well as improved physical characteristics consequent thereon, e. g., greater speed of recovery from strain, increased pliability, and enhanced recovcry from deformation, as, e, g, creasing, and also possessing greatly improved dyeing characteristics. This invention has as a. further object the appropriate processing of bodies consisting of such polyamides, in order to capitalize most elfectlvely on the said capacities and characteristics. Still further objects will appear either expressly or impliedly hereinbclow.

The aforesaid primary object is accomplished by heating in the molten state at amide-formmg temperatures a mixture of at least two preformed synthetic linear polyamides, at least one of which is per se soluble in a member of the class consisting of water, aliphatic alcohols concoining less than five carbon atoms, and mixtures of water with aliphatic alcohols containing less than five carbon atoms, and at least one other polyamide of which is per se insoluble in said member, and continuing the heating until a homogeneous melt blend is obtained, and preferably until not more than 10 per cent of the first mentioned polyamide is extractable from the product oy prolonged solvent treatment thereof with the aforesaid member, on cooling of the product.

The further object specified hereinabove is accomplished by treating the solidified melt blend, in whatever form desired, e. g., filaments or films. with the said member. In this treatment the letter, i. e., water, short chain aliphatic alcohol, or mixture of water and short chain aliphatic alcohol functions as a swelling agent, and will be referred to as such.

Generally, the preferred swelling agent is water or steam, the same being applied to the mixedpolyamide structure at elevated temperatures and for considerable periods of time. Consequently, the invention will be described in detail, and illus trated in the examples and tables set forth hereinafter, with particular reference to those embodiments involving the melt-blending of watersoluble polyomides with water-insoluble polyarnidcs, and the utilization of water or steam as the swelling agent for the processing thereof. It is to be understood, however, that the invention may be practiced in embodiments which, though generally less advantageous, are nevertheless more or less effective, without the use of water or steam; the same being replaced, e. g.,

with mild organic swelling agents. Thus, low molecular weight aliphatic alcohols may be substltuted for the water or steam, a methanol-, rather than water-, soluble polyamide substituted for the water-soiuble component of the mixed-polyamide, and an alcohol-, rather than merely water-, insoluble polyamide being chosen for the remaining component of the mixed-polyamide.

In any case, the mixed-polyamide structure generally is oriented, as by cold-drawing or coldrolling, prior to subjection to the swelling treatment, and ordinarily is permitted to shrink more or less freely during the treatment.

The synthetic linear polyamides used in the practice of this invention are of the general type described in Patents 2,071,250, 2,071,253, 2,130,- 523, and 2,130,948. The polymers there described are high molecular weight products which are generally crystalline in structure showing X-ray powder diffraction patterns in the massive state, and which are capable of being cold drawn into fibers showing by characteristic X-ray patterns molecular orientation along the fiber axis. For the best fiber-forming properties the polymerizm tlon reaction should be continued until the intrinsic viscosity is at least 0.4.

These polyamides, generally speaking, comprise the reaction product of a polyamide-forming composition in which the molecules are bifunctional and contain two amide-forming groups, each of which is complementary to an amide-forming group in other molecules in said composition.

These polyamides as defined above or as otherwise identified hereinafter can be obtained, for example, by self-polymerization of monoaminomonocarboxylic acids, or by reacting a diamine with a dibasic carboxylic acid in substantially equimolecular amounts, it being understood that reference herein to the amino acids, diamines, and dibasic carboxylic acids is intended to include the equivalent amide-forming derivatives thereof. Amide-forming derivatives of the amino acids include the ester, anhydrlde, amide, lactam, acid halide, N-formyl derivatives, carbamate, and nitrile in the presence of water. Amide-forming derivatives of the dibaslc carboxylic acids comprise the monoand (ii-ester, the anhydride, the monoand di-amide, acid halide, and the following compounds in the presence of water: nitrile, cyanocarboxylic acid, cyanoamide, and cyclic imide. Amide-forming derivatives of the diamines include the carbamate, N-formyl derivative and the N,N'-diformyl derivative.

These linear polyamides include also polymers obtained by admixture of other linear polymerforming reactants, as for instance glycols in the use of polyester amides, with the mentioned polyamide forming reactants. In either instance the amide group is an integral part of the main chain of atoms in the polymer, and, in the case of the preferred polyamides, the average number of carbon atoms separating the amide groups is at least two. It should be noted, however, that the ratio of amide groups to other carbon-noncarbon linkages in the polymer chain should be at least 1:20 if the products are to exhibit polyamide properties to a significant degree.

n hydrolysis with hydrochloric acid the amino acid polymers yield the amino acid hydrochloride, and the diamine-dibasic acid polymers yield the diamine hydrochloride and the dibasic acid.

Although the fiber-forming polyamides are preferred, particularly in the case of the "insoluble" polyamides, this invention may also be practiced with the lower molecular weight polyamides obtained from selected reactants or by stopping the polymerization reaction before the fiber forming stage is reached.

Those of the polyamides which are soluble in water, the preferred swelling agent for the practice of the invention, are generally found among the class of polyamides in which heteroatoms of the oxygen family are present in the main polymer chain. Specific illustrations of such water solubic varieties, as well as of other types of waoer-soluble polyamides, will be found hereinafter, along with illustrative species of polyamides which, though insoluble in water, are generally soluble in those organic compounds which usually function as swelling agents rather than solvents for polyamides of the fibe1'forming varieties.

Ordinarily the mixed blend is prepared with the use of between 5% and 80 of the more soluble component. Where such component is designated hereinafter as being water-soluble, such designation will mean that it is soluble at least to the extent of 20% by weight in water at 25 C. The m'elt blending is effected at amideq'orming temperatures, the same being, in general. above C. It is desirable to use temperatures in excess of 200 C. and preferably in the range of 250 to 300 C. The upper limit generally is below 320 C. This limit will vary, however, by reason of the fact that the polyamides difier somewhat in the temperature at which deleterious thermal decomposition takes place. It is desirable to exclude oxygen during the heating.

The following illustrates a preferred mode of practicing the invention:

A water-insoluble polyamide and a water-soluble polyamide, each in oomminuted form, are heated together at amide-forming temperatures to effect complete fusion of the ingredients. the same being stirred until the mixture is substantially homogeneous to the eye, i, e. until the melt appears to form a single phase without discontinuity. The time required usually is 10 to 60 minutes. As will be shown later. there is evidence that at least some chemical reaction between the polymers occurs during the meltblending. The resultant mixed polymer has a melting point lying in general near the melting point of the higher-melting component, which will in general be the water-insoluble polymer, and well above the melting point of the true interpolyamide which would be formed by heating together in corresponding proportions the monomeric reactants from which the said watersoluble and the said water-insoluble polyamides respectively were obtained. The melting point of a polymer blend of this invention lies close to that of the water-insoluble component when this component comprises at least one-half of the original mixture. Since high-melting points are desirable in textile fibers, it is preferred to blend not more than 50% of the water-soluble component with the complementary amount of the high melting, water-insoluble polyamide, in order to avoid extensive lowering of melting point. In some instances sufiicient blending can be accomplished merely by mixing small flakes or chips of the water-soluble and water-insoluble polyamides and feeding the mixture to a meltspinning assembly in which the mixture is melted prior to extrusion into filaments or the like and is kept in the molten condition long enough to secure a substantially homogeneous blend. In general, however, superior results are obtained by eflecting melt blending, with stirring, prior to feeding the polymer to a melt-spinning or extrusion device.

With reference to the hereinabove-stated discovery that by far the larger proportion of the water-soluble polyamide in the product cannot be extracted by boiling water, it may b remarked that even in the case of melt-blends containing especially high proportions of water-soluble polyamides, onlyone-tenth or less of this component ordinarily is removed during 72 hours exposure to boiling water. In fact, the duration of ihe melt-blending in the preferred practice of the invention, may he defined as that period which will yield a product from which, on solidification, not more than of the soluble component can be selectively extracted.

It may he observed further that the products of this invention are characterized by their ability, as hereinabove indicated, to absorb large amounts of water under typical atmospheric con ditions (e. g. 50% relative humidity at C.), while retaining their strength and resiliency.

The water-soluble polyamide, polyQI-methyltriglycol aduiamide) which is advantageously used in this invention. as shown in Examples V and VI, herelnbelow, may be prepared as follows: Four hundred thirty-eight parts of adipic acid and 546 parts of Nil-dimethyltriglycolcliamine CHaNHCHzCHzOCHzCHzOCl-lzCHzNHCl-ial are dissolved in 1600 parts of ethanol, and the solution is evaporated nearly to dryness. The di amine-diacid salt obtained is purified by recrystallization from ethanol. The salt is polymerized by heating it for 3 hours at 220 C. in a sealed vessel, for 3 additional hours at 250 C. under atmospheric pressure, and finally for 0.75 hour at 250 C. in vacuo. The polymer is a colorless, transparent. viscous fluid which sets is a. brittle class at -'l5 C. and is miscible with water in all proportions at 25 C. It has an intrinsic viscosity of 0.35.

The practice of this invention is illustrated in the following examples, in which the parts are given by weight.

EXAMPLE I One hundred twelve parts of polyhexamethylone adipamide water-insoluble; intrinsic viscosity, 0.80; melting point 250 C. in air) in the form of small chips and 48 parts of pulverized poyiriglycol adipamide (water-soluble; intrinsic viscosity 0.73; melting point 150 C.) are placed in a vessel from which atmospheric oxygen is exhausted by successive evacuation and admission of oxygen-free carbon dioxide. The filled vessel is then heated in a bath of boiling dibenzofurane vapor 287 C.), complete fusion of the contents thus being efiected. The molten mass is stirred until substantial homogeneity results. After cooling the mixture melting point 250 C.) the solidified melt-blend is transferred to the appropriate apparatus and converted into a yarn of continuous filaments as described in U. S. 2,130,948.

The yarn is processed by cold-drawing, plying and twisting to a thread of filaments which is 133 denier in weight and twisted 6 turns per inch. The sensitivity of this thread to moisture is man ifested in its behaviour when exposed to superheated stearn. At 140 C., the steamed threads shrink 17% in length during 4 hours, while under the same conditions threads of polyhexamethylene adipamide shrink only 5%. The yam subsequently is woven in a plain weave taffeta fabric Also denominated N-MMhyl polytriglycnl mllpumill lmrelnbuluw.

Ill)

measuring in the warp 120 threads per inch and in the woof 56 threads per inch. Exposure of this fabric to super-heated steam at 140 C. for 4 EXAMPLE II An intimate mixture Comprising parts of polytriglycol adipamide having an intrinsic viscosity of 0.82 and 65 parts of polyhexamethylene adipamide of intrinsic viscosity of 0.84 is prepared by melt, blending to substantial homogeneity during 30 minutes heating at 287 (3., with thorough stirring at intervals during the heating. A him of this composition absorbs 9% of its weight of water when allowed to come to equilibrium with moist air at 50% relative humidity and 25 C. Under these typical atmospheric conditions, the completely oriented film possesses unusual elasticity in the direction of orientation and recovers nearly completely after being stretched almost to the breaking point, which with different specimens is 30 to and in some instances In contrast with this unique elasticity, a film melt-cast irom polyhexamethylene adipamide stretches reversibly only to the extent of 5 to 10%, or at most 20%, and absorbs only 2 to 3% water at relative humidity and 25 C.

The blenzl of water-soluble and Water-insoluble polyamides is converted to yarn (100 denier,

30 filaments, 10 turns per inch twist) and woven in a plain weave, taffeta fabric measuring 109 threads per inch in the warp and '77 threads per inch in the wool. The water sensitivity of the constituentfibers permits unusual effects to be developed in this fabric. For instance, when it is exposed for 1 hour to ihe action of steam at 15 to lbs/sq. in. absolute pressure (1. e. to (3.), the fabric acquires the elasticity of mildly vulcanized rubber, and shrinks much more than a similar standard fabric of polyhexamethylene adipamide yarn. The following table shows how the degree of shrinkage may be pro-determined by adjustment of the steam pressure and the temperature, besides furnishing comparative data with respect to a similar fabric of polyhexamethylene adipamide yarn.

TABLE I Shrinkage of steam-treated fabrics Shrinkage of fabric When the foregoing mixed polyamlde fabric is soaked or boiled in water and then subjected to moist heat along with mechanical pressure against its face for 30 seconds. it develops extraordinarily good recovery from creasing. Such a treatment advantageously may be carried out by calendering the wet fabric. The crease angle, a measure of the percentage of crease recovery, is determined by measuring the angle from the horizontal to which a folded 1 inch square of fabric returns in 30 seconds, upon be ing allowed to unfold after the crease has been set in by the pressure of a 1 kilogram weight for 1 minute. Wet calendering temperatures of 150 to 220 C. applied to the said fabric produce finished cloth whose crease recovery is considerably greater than that of an otherwise identical fabric woven from polyhexamethylene adipamide yarn, as shown in the following table.

TABLE II Crease recovery of wet fabrics l "Crease EXAMPLE III A mixture of 150 parts or polytn'glycol adipamide (intrinsic viscosity, 0.83) and 850 parts of polyhexamethylene adipamide (intrinsic viscosity, 0.84) is melt blended by heating with intermittent stirring for about 30 minutes at 285 C. and then is melt-spun at about 280 C. into filaments which are converted by the usual procedures to yarn (90 denier, 30 filament, turns per inch twist) and thence to a plain weave taffeta fabric measuring 100 threads per inch in the warp and '10 threads per inch in the woof. The water-sensitivity comerred on the fabric by the presence of the water-soluble but unextractable component of the yarn is such that wet-calendering confers on the fabric unusual and highly desirable crease recovery, the same being approximately of the order of that shown in the case of the mixed-polyamide fabric of Table II, and contrasting sharply with the crease recovery of polyhexamethylene adipamide fabrics of the prior art.

Polyhexamethylene adipamide has poor receptivity for vat colors. and, furthermore, these dyeings crock badly. These difficulties are overcome by the use of polytriglycol adipamide melt blended with polyhexamethylene adipamide. Skeins of yarn melt-spun from the blend containing of the water-soluble polyamide component and 85% polyhexamethylene adipamide are dyed with vat colors by the sodium hydrosuifite method commonly used in commercial dyeing practice. Table III lists a comparison of the receptivity 0f the yarn with that of rayon 1 and with that of polyhexamethylene adipamlde, when skeins of the various fibers are dyed in individual baths. As can be seen from the table, the yarn prepared from the water-soluble and water-insoluble polyamide components has a receptivity for vat colors equal to that of rayon. Furthermore, these vat dyeings on the yarn oi the blended polymer do not crock.

llhe term. ray0n." as used lnthis specification, is intended to designate regenerated cellulose rayon, of the type spun (rom viscose.

Taste m Dye ab 1 Conoensorbed by ggi gg' 253,33 tretion yarn or 15% Dye color index is o. by by 3 8%; PH MA 8 rayon Q 8 i-lMA Yam Yam l Anthraquinone vat dye having color 52- Percent Percent Percent Percent dear No. 1113 3 40 no Anthraqulnone vat dye having color ini dex No. i132. on y m a s0 Anthraqulnone vet I 1 dyo having color ini rlcx No. 1163 i s (l6 1o 06 Indlgoid vat dye havlnz color index No.

1 PTGA-PO1 'trlglycol adlpamldc. J PHMAP0 yhexamet'oylene adlpmulde.

Skeins of yarn melt-spun from the product obtained from 15% of the Water-soluble component and 85% polyhenamethylene adipamide. skeins of polyhexamethylene adipamide yarn, and skelns of rayon are dyed in individual baths containing direct colors. As can be seen in Table IV the yarn containing the water-soluble and waterinsoluble polyamlde component has a receptivity comparable to that of rayon for direct colors.

TABLE IV Dye Coucenggf sg i Dye ab- Dye abl ye color index tratlon un sorbed by sorbed by .\'o. of dye PTO PHMA l rayon bath 5 yarn yarn PHMA I Direct dye having oolor index No. Per can! Per cent Per renl Per cm! 375 2 as as I us Direct dye having color index No. 382 l or, I 2:, l on Direct dye having j 1 color index No. i l 365.... 2 EL: 25 D0 l PTOA-Polyirinlycol adlpmnlde,

1 lliMA-Pulyhexnmethyleno ndlpuulidc.

Skeins of yarn melt-spun from the blend prepared from 15% or the Water-solub1e component and 85% of polyhexamethylene adipamide, skeins of polyhexamethylene adipamlde yarn, and skeins of silk are dyed in individual baths containing neutral dyeing acid colors. As can be seen in Table V the yarn prepared from the melt blend of the water-soluble and water-insoluble polyamide components has a receptivity comparable to that of or greater than that of, silk for neutral dyeing acid colors.

TABLE V b b 'd n i Conceu- 8 SM e y Dye ab- D ye color index tration 2, sorbed by D39 x0. Ol'dyG 3 3 PH MA 2 Sqrbed I bub PT 8.5. and yam silk yarn I PHLIA Neutral dyeing 2 acid dye having Per cm! Per cent Per C171! Irn'en! index No.833. 4 l 03 37 1 0R Neutral dyelngacid dye having 1 color index No. I l i 430 2 y I2 63 I l"FGA-Pol 'triglycol udlpnmldc. I PUMA-Po yhoxamcthylono odipamldo.

When knit goods prepared from polyhexamethylene adlpamide yarns difiering in the delessees? gree to which they have been drawn, in ilie solid state, by as much as 4% are dyed with acid. dimet, or vat colors, a. pronounced color iunction appears at the union of the sections oi fabric con taining the differently drawn yams, the section knit from the lesser drawn yam absorbing more color than the section. knit from the more highly drawn yam. Knit goods prepared from the meltspun yam of polytriglycol azilnemicle and 85% polyhexemethylene erilpemirle dillering in the degree to which they have been. dravm, in the solid state, by as much as 4% are dyed uni iormly and evenly with cold, direct, and vet colors. Accordingly, the level-dyeing properties are lmoroved as well as the dye receptivity of the modified polymer over similer properties of polyhexemethylene edlpamide.

The polyemlcles of this invention have :2. greater efifinity for basic colors and chrome clues than do pclyemicles such as polyhexemetliyleue snip amide. Typical examples of useful basic colors are those having color indices of 657, "49, and 815. Examples of useful chrome dyes are those of color indices 109, me, 216, 219, and 720.

The polyamides of this invention also have good efiinity for dyestuffs of the cellulose acetate class. Thus fabrics knitted from cold drawn yam spun from the melt blended polyemide of Example III are satisfactorily clyecl in a 1% bath of cellulose acetate color having Color Index 1 1-43.

EXAMHJE IV By the procedure described in the foregoing exsimples, a. series of melt-"blends are prepared by heating with intermittent stirring at 135 C. for about minutes polytz-iglycol erllpemide Kin trinslc viscosity, $.84.) and polyhexemetliyiene edlpemicie (intrinsic viscosity, 0.63) in varying proportions. The physical properties which cherecterize the resulting compositions are indicated in the following table, along with corresponding data. for the unblended components and for the interpolymers mode from the proportions of the corresponding monomeric ingredients. It will be noted that the melting points of the meltblends of pro-formed polymers are significantly higher than the melting points of the mt-erpolymers.

TABLE VI Properties of meit=blends of gcolytriglycol cdieamide and pol hexomethylene odigsemide I i l Proportions of l ingredients I Melt-blend i 1\ ielt- Interl lie-file we... g g PTGA PH A 2 point point absorption gz g i (satggaed water i 1 l extraction I NC. Per cent Per cent 4; 100 217 241 9.0 0 0.5 99.5 247 9.1 0 1 90 246 f 9.1 0.1 3 2 9:; 245 9.0 0 I l m; 244 I x0. 1 o. s f s 92 I 242 l 10.7 0.6 a 20 R0 244 224 13. 7 l. 2 j rss 242 213 21.1 2. 2 50 240 190 :n. o 4. 5

cs 35 2.35 we so 20 21s 1 155 i 90 10 1: 5 4X52 g 100 3 use I H 100 I P'lGA-Polytrlglycol adipamidc.

1 PHMA-Polyhexumethylene adlpamlrlc. B For comparison.

Loses strength.

5 Dissolves.

intimate mixtures of N-methyl polytriglycol adipamlde (intrinsic viscosity, 0.35) and polyhexametlivlene adlpamide (mtrinsic viscosity, 0.81) in the proportions shown in the following table are prepared by melting them together with intermittent stirring in the absence of oxygen at 285 C. for about 30 minutes. The table furnishes e. guide to the proper choice of proportions necessery for obtaining products with desired melting ncints and water absorption or extraction properties.

TABLE VH Proportions ol lncrmllcms Water ebsorp- Proportion tlon of meltof weight iggg t bletncli) t lostton so um e a we or N'M PEGA 1 PH MA s 0' motion Percent Percent C. Percent Peru n5 Tssm: VIH

ye absflolrbed rby D Concentroms 0 ye Dye color index No. clan of g; ggi fi m,

dye murrfis PHMA a and 0 PHMA l VAT COLORS Anthmquinone dye hev- Percent Percent Percent 12%;;101 index No. 1163. 5 96 50 Am qulnone dye having color index No. 1113. 5 96 40 DIRECT COLORS Direct dye having color index No. 365 2 95 25 Direct dye having color index No. 382 2 95 25 Direct dye having color index N o. 375 2 95 25 ACID COLORS Acid dye having color indcx N o. 114 2 25 Acid dye having color inflex No. 430 2 12 l N-M P'lGA-N-methyl polytriglycoi adipamide.

9 PHMA-Polyhexamethylene adlpemido.

EXAllriPIE VI A melt-blend is formed by stirring and heating for shout 30 minutes at 285 C. in the absence oi oxygen parts of N -methyl polytriglycol edipemide (intrinsic viscosity, 0.35) and 900 parts of an interpolymerization product (melting point, 161 0.; intrinsic viscosity, 1.00) of 40% hexamethvlenediammonium edipete, 30% hexamethvlenediemmonium sebacete, and 30% epsiloncaprolactam. Pellicles of this composition (melting point, C.) are conditioned to diflerout moisture contents at 25 C. by the following methods: (1) thorough drying in a. chamber dehydrated by phosphorus pentoxide, (2) exposure for 24 hours to atmosphere st 59% reletive humidity, and (3) soaking in water. The pellicles with the highest moisture content (conditioned by method 3 are very resistant to the usual embrittling influence of low temperatures. For example, they are still capable of being cold drawn when cooled to -65 C. and therefore are nseess'i Melt-blended mixtures of Water-soluble polyamides with weterdnsoluble polyemides other than those already specified, together with figures furnishing a guide to the proper choice 01' proportions for obtaining optimum balance between melting point and other characteristics, will he found in the following table.

TABLE K Melt blends of water-soluble and water-mach wide nolyamides Wow-nimble pclynmide (1) want-momma polynmlde 2) Mew! (1}.(2) point C. A N-mcthyl poiytriglyeol sdipemide. lnierpolymsrlzation product of 60% hemmethylenedicmmonliun edl- :90 180 pens and 40% epsilon-ceproleetem. i0 :80 i715 i0 40:60 135 Eni/emoiymerization product oi 43% hemmethylene-dinmmonlum adi- 40:60 116 mte. 33% hemmethylenediammonium aebncato and epsiloncmzoiscmm. if if "i"; 'ii'c 'zh' aggg {*0 e o amnion enese am e z ym an 10:90 2 .....do.. "(56)..-. 20M) 210 do :65 214 50:50 210 6:95 202 10:90 206 20:80 204 35:65 192 do 50:50 2W lintorpolymerisation product of 60% hemmethylenedismmonium B 6:95 186 pate and epailon-capmlsctam. 10:90 185 20:80 184 35:65 183 :50 171 table new IX Gold crack temperatures of moisture-conditioned films Water absorption Cold crack melt-blend mpmwm at 25 C.

Method oi conditioning WJIZPLE VII The intemolymerization product (soluble in 80:20 mixture of ethanol and water) of 02 hexamethylene diammonium edipate and 40% of epsilon-caprolectam is melt-blended at 285 C. with stirring with an equal weight of fiber-forming polyhexamethylene adipnmide (insoluble in ethanol-water mixtures) until a homogeneous product is obtained. The resulting melt-blend is spun into yarn and the yarn oriented by coldclmwing until the yarn had 9, residual elongation Percmi 7 55 of about 20%. As shown by the following table, if; this yarn has better dyeing properties than yams 3.1 --25 to -3c so spun from polyhexamethylene adipamide alone.

' new m Dye absorbed Dye absorbed by- M} fi l D b bed Condmtmn erpo ya a W merization b polyhexa- Dye fg gig product and iiethylene pol hexoedipemide Rayon Silk met ylene adipcmide Per cm! Per cent Per cent Per cent Per cent Neutral dyeing acid having 0. I. No. 114..." 2 Neutral dyeing acid having 0. i. No. 430 2 to Direct die having; 0. I. No. 618.." 2 Vol dye ovina L I No. me 6 Vet (lye having 0 I No. Pr. 124 6 00 Vat dye having 0. 1. No. 1101 5 80 Suitable water soluble polytriglycolamides other than those varieties which have been disclosed hereinabove, include polytriglycol RN- piperazinedlacetamide, polytriglycol N-methyliminodiacetamide', polytriglycol -hydroxy-L9- nonanedicarbonamide, polytriglycol diglycolamide', and the interpolymerization products of: trlglycoldiammonium adipate (85 parts), hexamethylenediammonium adipate (14 parts), and triglycoldiammonlum d-ketopimelate (1 part): or triglycoldiammonium adipate (85 perm), hexamethylenedlammonium adipate parts), and triglycoldiammonium 4-ketopimelate (5 parts); or triglyccldiammonium adipate and fi-aminocaproic acid containing at least 75% of the former; or triglycoldiammonium diglycolate (50 parts) and hexamethlylenediammonium glycolate (50 parts); or triglycoldionium diglycolate (70 parts) and hexamethylenediammonium adipate (30 parts) or triglycoldiammonium adipate and decamethylenediammonium sebacate containing at least 90% of the former; or triglycoldiammonium adipate and hexamethylenediammonium sebacate containing at least 85% of the former; or triglycoldiammonium adipate and hexamethylenediammonium adipate con-.

tainins at least 85% of the i'ormer.

Of the water-soluble polyamides Just listed, those marked with an asterisk ordinarily are to be preferred, since they are soluble at least to the extent of 50% by weight in water at 25 C. The remaining polymers in the list are satisfactory in many instances, however, since they are at least soluble by weight, in water at. C. The significance of the stated 20% or, preferably, 50% solubilitles arises from the fact that the extent of unique characteristics possessed by, or producible in, the products of the invention corresponds generally to the degree of inherent solubility of the more soluble polyamide of the mixture in water, or whatever other swelling agent may be employed in place thereof.

Additional examples of water-soluble polyamides suitable for use in the practice of the invention include polydiglyool diglycolamide, polyethylene N-methyliminodiacetamide, polydiglycol N-methyliminodiacetamide, and poly-4,7- dioxadecamethylene adipamide.

Mixtures of two or more watensoluble polyamides of course may be employed as the watersoluble component. It is to be remarked, furthermore, that the suitable water-soluble polyamides are not limited to fiber-forming polyamides, although it is desirable that these polyamides have intrinsic viscosities of at least 0.2.

As the water-insoluble component, any fiberforming polyamide or interpolyamide, or a mixture of two or more of them, advantageously may oe used. In addition to the water-insoluble polymers mentioned in the foregoing examples, the following are suitable: polytetramethylene adipamide, polytetramethylene suberamide, polytetramethylene sebacamide. polyoctamethylene adipamide, polydecamethylene p-phenylenediacetamide, poly-p-xylene sebacamide. polypentamethylene adipamide, polypentamethylene sebacamide, and Q-aminononanoic acid polymer. Since it frequently desired to achieve a high melting point in the product, water-insoluble polyamides having melting points above about 235 C. are preferred. The first six of the polyamides just listed are examples 0! such preferred ingredients.

As is evident from Examples IV and V, the properties or the polyamide mixtures which are responsive to the hot water or steam treatments in accordance with the invention, depend on the proportions of water-soluble and water-insoluble ingredients. The optimum qualities are achieved by the use of water-soluble polyamide in the preferred proportions of 15% to 50%. since the highly water-soluble polyamides are more effective than their less soluble analogs, however, when used in the same proportions, it has been found desirable to use higher proportions, preferably at least 15% or higher, of the water-soluble component, if it is soluble in water to the extent of'iess than 50% by weight.

The melt-blends of this invention are not identical with simple mixtures or with the corresponding interpolyamides, as demonstrated by the following facts: (1) The major proportion of the soluble component (s) of th melt-blends is not extractable, while non-melt-blended mixtures (including heterogeneous melts) such as are obtained by mixing the components in a mutual solvent which is subsequently evaporated, can easily be separated into tlfe-original component polyamides by treatment with a selective solvent; (2) as indicated in Example IV, the" melt-blends have significantly higher melting points than the corresponding interpolyamides. A plausible explanation for these facts is that the process of melt-blending involves some chemical reaction, presumably, amide interchange. which unites the molecules of the constituentsto a slight degree; but in postulating this explanation the applicants 'do not intend to be in any way bound thereby or limited thereto.

Although the water-soluble plus water-insoluble polyamide mixtures in most instances are preferred, in view especially of the relatively low cost of water as compared with other swelling agents and its use in dyeing and finishing operations, there are several counter-balancing advantages in the use of mild organic swelling agents, rather than water, which advantages on occasion may outweigh those inherent in the use of water. In such case the water-soluble polyamide component can be replaced with a component soluble per se in the said organic swelling agent, as hereinabove explained. The said relative advantages of the organic swelling agent may include ease of removability, as in the case of low boiling alcohols, increased activity at lower temperatures as compared with water, and decreased tendency to corrode equipment and consequently to contaminate the mixed-polyarnide article undergoing treatment.

The mild swelling agent which may be employed in the practice of the invention generally are hydroxylated organic substances, which include not only the low molecular weight aliphatic alcohols such as methanol, ethanol, isopropanol. and butanol, but also ethylene chlorohydrin and benzyl alcohol.

Typical alcohol-soluble polyamides suitable for melt-blending with alcohol-insoluble polyamides,

such as polyhexamethylene adipamide, in the practice of the invention, include poly(N-methyltriglycol adipamide) and the interpolymerization product of hexamethylenediammonium adipate (40 parts), hexamethylenediammonium sebacate (30 parts), and epsilon-caprolactam (30 parts). Polyamides soluble in alcohol-water or alcoholchloroform mixtures can also be used as the soluble components. An example of this type is the polyamide derived from hexamethylenediammonium adipate (preferably 40 to 60 parts) and 6- aminocaproic acid (preferably 60 to 40 parts).

Polyester-amides such as those derived from diamine, dibasic acid and glycol, also are useful, provided a swelling agent is chosen which, though a solvent for them per se, is a non-solvent for the polyamide with which they are to be melt-blended. As a rule, the solubility of the ester-amide polymers increases as the percentage of ester content increases.

One of the foremost advantages of the mixedpolyamide products of the invention is their elasticity in the form of fabrics and foils. The elastic fabrics obtained by finishing treatments such as described in Examples 1, II and III are suited for the types of garments which require a greater extensibility than can be attained with natural fibers. Fabrics possessing unusually high recovery from creasing, such as that of Example II, are, like wool, in great demand for textile uses, e. g. for garments in which impermanence of accidental creasing is highly desirable. Such fabrics are distinctly superior in this respect to the more crease-retentive synthetic fabrics of the prior art.

In connection with the superior dyeing characteristics of the mixed polyamide products of the invention, illustrated in Tables III-V, VIII, and

XI, hereinabove, it -may be remarked that the products have especially good receptivity for dyes in printing. A wide variety of dyes can be used in the printing pastes. Useful dyes include vat colors, e. g. those of color indices 1095, 1101, 1133, 1151, 1184, and 1212, acid colors, e. g., those of color indices 27, 234, 561, 581, 801, and 1053; direct colors, e. g. those of color indices 561, 581, and 814; basic colors, e. g. those of color indices 815 and 922; chrome colors, e. g. color having index number 720; oxidation colors, e. g. oxy black base (p amino diphenyl amine) Celanthrene colors, e. g. l-methyl amino anthraquinone; and acetamide colors, e. g. dispersible dyestufi from aniline azo alpha naphthylamine azo phenol. A few typical examples follow.

EXAMPLE VIII The printing paste used consisted of 20 parts of vat color having Color Index No. 1184 and 80 parts of a composition prepared by incorporating 15% potassium carbonate, 15% sodium sulfoxyle ate formaldehyde and 5% glycerine in a suitable thickening gum such as starch, British gum, tragacanth or karaye. The paste is printed on poly hexamethylene adipamide fabric and on a fabric made with melt-blended polyamide of the type described in Example III. After printing the fabrics are partially dried, aged for 5 minutes in vat color ager, oxidized, rinsed, soaped, rinsed, and dried to give a blue pattern in the imprinted areas. The blue pattern is brighter on the fabric made from modified polyamide than on the polyhexamethylene adipamide fabric.

Discharge prints can be made with the above paste printed on grounds dyed with dye of Color Index No. 487 (Scarlet) or Acetamide Blue GFA.

EXAMPLEIX A printing paste consisting of 2 parts of 1- methyl amino anthraquinone, 28 parts of water, and 70 parts of textile gum is printed on fabric made of melt-blend polyamide made by the proces of this invention. After drying, the fabric is aged for 10 minutes in a vat color ager, soaped, rinsed, and dried. A brilliant scarlet print is obtained.

For discharge printing the above printing paste can be mixed with 10% of stannous chloride or titanous chloride and printed on a ground dyed with p-amino acetanilide azo para cresol to give a scarlet illumination design on a yellow ground.

The mono nucleus anthraquinone bodies used as dyestuffs may be monoor poly-amino anthraquinones which may be substituted in the nucleus or in the amino group or in both.

The resilient pellicles made of the blends of this invention are especially useful as self-supporting films for wrapping purposes and the like.

Since many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. A process for obtaining an improved polyamide composition having a relatively high melting point and enhanced amnity for dyestuffs which comprises heating at amide-forming temperatures below that at which destructive decomposition occurs, a molten mixture of at least two preformed synthetic linear polyamides, at least one of said polyamides being water soluble at least to the extent of 20% by weight at 25 C. and at least another of said polyamidesbeingwater insoluble, said soluble to insoluble polyamides being by weight in the range 5:95 to :20, each of said preformed polyamides being one which on hydrolysis with hydrochloric acid yields substances of the class consisting of (a) monoaminomonocarboxylic acid hydrochlorides and (1 mixtures of diamine dihydrochloride and dibasic carboxylic acid, continuing the heating at said amide-forming temperatures until the molten polyamides form a single phase without discontinuity and until a substantially homogeneous product is obtained on solidification from which not more than 10% of said soluble polyamide can be selectively extracted by water, then solidifying said polyamide composition.

2. A process for obtaining an improved polyamide composition having a relatively high melting point and enhanced affinity for dyestuffs which comprises heating at amide-forming temperatures between 250 to 300 C., a molten mixture of at least two preformed synthetic linear polyamides, at least one of said polyamides being soluble at least to the extent of 20% by weight at 25 C. in a solvent selected from the group consisting of water, aliphatic alcohols of less than live carbon atoms and mixtures of water and said alcohols, and at least another of' said polyamides being insoluble in said solvent, said soluble to insoluble polyamides being by weight in the range 15:85 to 50:50, each of said preformed polyamldes being one which on hydrolysis with hydrochloric acid yields substances of the class consisting of (a) monoaminomonocarboxylic acid hydrochlorides and (b) mixtures of diamine dihydrochloride and dibasic carboxylic acid, continuing the heating at said amide-forming temperatures until the molten polyamides form a single phase without discontinuity and until a substantially homogeneous product is obtained on solidification from which not more than 10% of said soluble polyamide can be selectively extracted by said solvent, then solidifying said polyamide composition.

3. An improved polyamide composition having a relatively high melting point and enhanced affinity for dyestuffs comprising the reaction prodnot obtained by heating at amide-forming temperatures below that at which destructive decom- 

